NTI Trinity TRX 1 08 — Water Pressure Too Low
1 08
Water pressure too low. The boiler shut off because the water pressure inside the heating circuit is too low; causes include air in the system or lack of water pressure, improper boiler piping, an incorrectly located expansion tank, or a malfunctioning pressure switch with a bad wire harness. The table classifies it as Blocking (Auto Reset).
Applies to
This low-water or pressure protection code is displayed by the TRX Series I control on TRX Series I models up to 150C (TRX085, TRX110C, TRX120, TRX150C), as documented in TRX 085–150C Installation and Operation Manual, doc 420010970805 Rev 01.24.23, Part 13-B Boiler Error Codes (420010970805 Rev 01). Codes can differ between controller generations, so always check the manual that matches your unit.
- NTI Boilers Trinity TRX
- NTI Trinity TRX085
- NTI Trinity TRX120
- NTI Trinity TRX150
- NTI Trinity TRX199
- NTI Trinity TRX110C
- NTI Trinity TRX150C
- NTI Trinity TRX199C
Controller: TRX Series I control. Source manual: 420010970805 Rev 01 (2023-01-24).
Why a code is not a diagnosis
A water-pressure or low-water code can mean a genuine leak or empty system, a failed expansion tank, a faulty fill valve, or a sensor problem. The appliance does not distinguish these.
Safe things to observe
- Read the pressure gauge and compare it with the normal cold-system pressure your installer set.
- Look for drips or wet spots near the appliance, pipes and the relief-valve discharge.
Do not
- Do not keep re-pressurizing a system that keeps losing water.
- Do not cap a relief-valve discharge pipe.
How professional service helps
- A technician finds and repairs the leak, checks the expansion tank and fill assembly, and verifies the sensor circuit.
Where ROMA provides on-site service
On-site service is currently offered in Greater Vancouver, BC, including Vancouver, Burnaby, Richmond, Surrey, Coquitlam, North Vancouver, West Vancouver, New Westminster, Port Coquitlam, Port Moody, Delta, Langley, Maple Ridge, Abbotsford, Chilliwack, White Rock, Pitt Meadows, Tsawwassen, Anmore, Lions Bay, Belcarra, Bowen Island, Mission. Everything else on this site is reference information you can use anywhere in Canada.
Parts and service
Parts commonly involved
These parts appear in the documented text for this alert. A code reports a condition, not a failed part — a technician confirms the cause by testing before anything is replaced.
Low-water cutoff
A low-water cutoff is the safety device that stops a boiler from firing when there is not enough water inside it.
What a technician checks →Expansion tank
An expansion tank gives heating water somewhere safe to go as it heats and grows, keeping pressure stable and protecting the relief valve.
What a technician checks →
Service for this alert
- Gas Boiler Repair
Licensed gas technicians from ROMA Heating & Cooling diagnose and repair residential and light-commercial gas boilers across…
Every boiler part explained — what it does, how it fails and what a technician checks.
Documented for NTI Boilers Trinity TRX.
Frequently asked questions
Can I clear this code myself?
Clearing a code without fixing its cause usually just brings it back. Note the code, check the safe items on this page, then call a licensed technician. If your appliance manual describes a user reset for this exact code and it stays away, no call may be needed.
Boiler locked out? Call with the alert text ready.
The brand, model and this alert are passed along when you request service online, so the technician arrives prepared.
On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.
Sources and verification
- TRX 085–150C Installation and Operation Manual, doc 420010970805 Rev 01.24.23, Part 13-B Boiler Error Codes · 420010970805 Rev 01 · accessed September 7, 2026
Facts checked September 7, 2026. Last updated September 7, 2026. Technical reviewer: not yet assigned.